"Despertate Paparulo" is El Cuarteto de Nos from Uruguay doing what they do best: a cheeky, slightly absurd story told at full speed. The title already sets the joke. Despertate (wake up) uses the Uruguayan vos form, and paparulo is Rioplatense slang for a fool or a dope. So the whole song is basically someone shouting "wake up, you dummy!"
The lines bounce between waking and dreaming. Someone is "medio dormido en el sillón" (half asleep in the armchair), and the chorus keeps telling him he is "soñando, está soñando" (dreaming, he's dreaming) while Montevideo goes on without him. In the dream he gets the good life: "mujeres, caviar y champán" (women, caviar and champagne), a yacht that "se balancea" (rocks) on the sea, and "chicas marineras" (sailor girls) who "reclamaban acción" (demanded action). Every time it gets good, the same hook drags him back: "cuando termine de despertar" (when he finishes waking up).
For a learner, the song is a fun place to hear how Uruguayans speak. Listen for the vos imperatives like despertate instead of the textbook despiértate, and for how often despertar (to wake up) and soñar (to dream) come back. The words we have here are rough in places, so treat the clear lines as your study material and enjoy the rest as rhythm.